What is type 1 diabetes?

Insulin is a hormone that helps the body's cells use sugar (glucose) for energy. It also helps the body store extra energy in muscle, fat, and liver cells. Without insulin, this sugar can't get into your cells to do its work. It stays in your blood instead. And then your blood sugar level gets too high.

High blood sugar can harm many parts of the body, such as the eyes, heart, blood vessels, nerves, and kidneys. It can also increase your risk for other health problems (complications).

Type 1 diabetes can occur at any age, but it usually starts in children or young adults. That's why it used to be called juvenile diabetes.

Type 1 diabetes is different from type 2 diabetes. In type 1 diabetes, the body stops making insulin. In type 2, the body can't use insulin the right way. Over time with type 2, the body doesn't make enough insulin.

There isn't a cure for type 1 diabetes. But with treatment, people can live long and healthy lives.

What causes type 1 diabetes?

The body makes insulin in beta cells, which are in a part of the pancreas called the islet (say "EYE-let") tissue. Type 1 diabetes starts because the body destroys those beta cells. Experts don't know why this happens.

Some people have a greater chance of getting type 1 diabetes because they have a parent, brother, or sister who has it. But most people with the illness don't have a family history.

Other things that increase the risk of getting type 1 diabetes are being white and having islet cell antibodies in the blood.

What are the symptoms of undiagnosed type 1 diabetes?

Symptoms of diabetes are:

Being very thirsty.

Urinating a lot.

Losing weight without trying.

Being hungrier than usual (sometimes).

Blurry eyesight.

These symptoms usually appear over a few days to weeks. Sometimes people notice symptoms after an illness, like the flu. They may think that the diabetes symptoms are because of the flu, so they don't seek medical care soon enough.

If you wait too long to get medical care, you may get diabetic ketoacidosis, which is very dangerous. Symptoms of this problem include:

Cause

Type 1 diabetes develops because the body's immune system destroys beta cells in a part of the pancreas called the islet tissue. These beta cells produce insulin. So people with type 1 diabetes can't make their own insulin.

The pancreas normally adjusts the amount of insulin it makes based on your changing blood sugar. When you have diabetes, your insulin injections can't control your blood sugar moment to moment, the way your pancreas would. So you may have high and low blood sugar levels from time to time.

Causes of high blood sugar

Causes of high blood sugar include:

Not getting enough insulin.

Eating more food than usual.

Stress and being ill (such as with severe flu) or having an infection, especially if you aren't eating or drinking enough.

Diabetic ketoacidosis

Sometimes a person's blood sugar level rises greatly before he or she knows something is wrong. Because insulin isn't available, the cells in the body are unable to get the sugar (glucose) they need for energy. The body begins to break down fat and muscle for energy.

When fat is used for energy, ketones-or fatty acids-are produced and enter the bloodstream. This causes the chemical imbalance diabetic ketoacidosis. This can be a life-threatening condition.

Low blood sugar

If you aren't able to tell when your blood sugar is too low (hypoglycemic unawareness), it's a good idea to test your blood sugar often.

Risk factors for high and low blood sugar

Tight blood sugar control. Tight control of blood sugar helps prevent complications, such as eye, kidney, heart, blood vessel, and nerve disease. But it does put you at risk for frequent low blood sugar levels.

Adolescence. The rapid growth spurts and changing hormone levels of adolescence can make it difficult to keep blood sugar levels within your target range. Your target range is the blood sugar goal you set with your doctor.

Eating disorders. Teens are often concerned about their weight and body image, and they may skip insulin injections to lose weight. Eating disorders can be much more common in girls and women of all ages who have type 1 diabetes.

Lipohypertrophy, which is fat and scar tissue that can be caused by repeatedly injecting insulin in the same place. The area may feel firmer than the skin around it. Injecting insulin into an area of fat and scar tissue means it may not be absorbed at the same rate each time, which could cause high or low blood sugars.

Gastroparesis. Damage to the nerves of the body can change how the stomach contracts when digesting food. Food can take longer to digest, which can make it harder to know when insulin will work after eating. This can lead to high and low blood sugars.

Thyroid or kidney problems. Too little thyroid hormone can slow metabolism, which can cause some medicines (like insulin) to stay in the body longer. This can cause low blood sugar. And when the kidneys are damaged, insulin may stay in the body longer, causing low blood sugar. The kidneys may also have problems making glucose, causing low blood sugar.

What Happens

It's not possible for injected insulin to work as well as a normal pancreas, so you will have high and low blood sugar levels from time to time.

Eyes

Feet and skin

You may have less feeling in your feet, which means that you can injure your feet and not know it. Common infections from blisters, ingrown toenails, small cuts, or other problems can quickly become more serious when you have diabetes.

If you get serious infections or bone and joint deformities, you may need surgery (even amputation) to treat those problems.

Heart and blood vessels

Nerves

High blood sugar levels can damage nerves throughout your body. This damage is called diabetic neuropathy. There are three kinds of diabetic neuropathy:

Diabetic peripheral neuropathy. This is damage to the nerves that sense pain, touch, hot, and cold. This type of nerve damage can lead to deformities such as Charcot foot. It can also lead to other problems that may require amputation.

Autonomic neuropathy. This is damage to nerves that control things like your heartbeat, blood pressure, sweating, digestion, urination, and sexual function.

Focal neuropathy. Most of the time, this affects just one nerve, usually in the wrist, thigh, or foot. It may also affect the nerves of your back and chest and those that control your eye muscles.

Kidneys

The kidneys have many tiny blood vessels that filter waste from your blood. High blood sugar can destroy these blood vessels. You won't have any symptoms of kidney damage until the problem is severe. Then you may notice swelling in your feet or legs or all over your body.

Hearing

High blood sugar can damage the small blood vessels and nerves in the ear, causing hearing loss.

Teeth

Gum disease can make it harder to keep blood sugar in a target range. And high blood sugar can cause gum disease, loss of teeth, and healing problems in the mouth.

Mental health

The stress of dealing with diabetes or the effects that diabetes has on your body can lead to depression.

Being depressed can make it hard to eat healthy foods and to find the motivation to exercise. All of these things lead to higher blood sugar. By getting help for depression, you'll feel better and may find it easier to stay motivated.

What Increases Your Risk

Risk factors are things that increase your chances of getting sick or having a problem. Risk factors for type 1 diabetes include:

A family history of type 1 diabetes. Having a family history of the disease increases the chance that a person will have islet cell antibodies or other autoantibodies that attack the cells in the pancreas that produce insulin. But it doesn't predict that a person will have the disease.

Race. White people have a greater risk for type 1 diabetes than black, Asian, or Hispanic people.

Presence of autoantibodies in the blood. People who have both a family history of type 1 diabetes and two or more autoantibodies in their blood are likely to get type 1 diabetes. Family members of people with type 1 diabetes can be tested to see if they have autoantibodies. People who are found to have autoantibodies may be able to take part in studies trying to prevent type 1 diabetes.

If it is hard to tell if you have type 2 or type 1 diabetes, your doctor may do a C-peptide test or test for autoantibodies. (Autoantibodies are produced when the body's immune system does not work right.) For example, many people with type 1 diabetes produce the autoantibody zinc transporter 8 (ZnT8Ab). People with type 2 diabetes or gestational diabetes do not produce ZnT8Ab.

There are several types of autoantibodies, and some people may have them even before they show symptoms of type 1 diabetes. For people with a parent or sibling with type 1 diabetes, testing for autoantibodies and a higher-than-normal blood sugar level may be done to screen for an early stage of type 1 diabetes.

These tests may not be able to confirm the type of diabetes you have. Getting a definite diagnosis may take months or years. In either case, your blood sugar levels will need to be controlled right away.

Tests to check your health

Check your blood pressure and start or adjust treatment, if needed. Nerve and blood vessel damage can result from high blood pressure, leading to heart problems and strokes. For more information, see the topic High Blood Pressure.

Check your feet for signs of problems, especially if you have had diabetes for a few years. Nerve damage in your feet makes it hard to feel an injury or infection. Take off your socks each time you see the doctor to be sure you both remember to check your feet. At least once a year your doctor will do a complete examination of your feet.

Have a hemoglobin A1c test. This blood test shows how steady your blood sugar levels have been over time.

These visits are also a good time to talk with your doctor about how you're feeling. It's normal to feel frustrated or overwhelmed with all there is to do. If you're having trouble coping, your doctor can help. And if your health is changing and you have complications from diabetes, work with your doctor to make the right medical decisions for you. With your health and quality of life in mind, problem-solve and plan with your doctor.

Tests to screen for complications

After you have had type 1 diabetes for 3 to 5 years, your doctor may recommend these tests.

A complete eye exam by an ophthalmologist or optometrist. High blood sugar levels from diabetes can damage your eyes. This test can find problems early. If you do not have any signs of diabetic retinopathy, your doctor may recommend less frequent exams. For example, you may have this test every 2 years.

A foot exam to check for diabetic neuropathy. Your doctor may look at your feet for sores and calluses at every visit. If you have one or more foot problems, you may need to have your feet checked more than once a year. A child who has diabetes may not need a thorough examination of his or her feet each year until after puberty.

A cholesterol and triglyceride test. Along with other measures, cholesterol levels can help you know your risk for having a heart attack or stroke.

A urine test, to check for protein. If protein is found, you'll have more tests to help guide the best treatment. Protein in the urine can be a sign of kidney damage (diabetic nephropathy).

A thyroid-stimulating hormone test. This test checks for thyroid problems, which are common among people who have diabetes. If the test is normal, your doctor may suggest you have the test again every 1 to 2 years.

Eye exams during pregnancy

If you get pregnant, you will need to have an eye exam sometime during the first 3 months. You'll also need close follow-up during your pregnancy and for 1 year after you have your baby. Pregnancy may increase your risk for diabetic retinopathy. If you already have eye disease and get pregnant, the disease can quickly get worse.

Regular medical checkups. You will get routine screening tests and exams to watch for signs of complications, such as eye, kidney, heart, blood vessel, and nerve diseases.

Not smoking.

Not drinking alcohol if you are at risk for periods of low blood sugar.

Blood sugars are easier to predict and control when mealtimes, amounts of food, and exercise are similar every day. So getting into a daily routine helps a lot.

Diabetic ketoacidosis

Some people find out that they have type 1 diabetes when they are admitted to a hospital for diabetic ketoacidosis. If their symptoms are severe, they may need to be treated in an intensive care unit.

Treatment for diabetic ketoacidosis includes fluids given through a vein (intravenous, or IV) to treat dehydration and to balance electrolytes, and insulin to lower the blood sugar level and stop the body from producing ketones.

The honeymoon period

If your blood sugar levels return to the normal range soon after diagnosis, you are in what is called the "honeymoon period."

This is a time when the remaining insulin-producing cells in your pancreas are working harder to supply enough insulin for your body.

Treatment during this time may include:

Keeping in close touch with your doctor.

Testing your blood sugar level often, to see if it is rising.

Taking very small amounts of insulin or no insulin. Even though you may not need insulin, some doctors prefer that you take small doses of insulin daily throughout the honeymoon period. This may decrease the stress on the pancreas.

Prevention

Currently there is no way to prevent type 1 diabetes, but ongoing studies are exploring ways to prevent diabetes in those who are most likely to get it. People who have a parent, brother, or sister with type 1 diabetes and are willing to participate in one of these studies should talk with their doctors.

Preventing diabetes complications

People who have type 1 diabetes can help prevent or delay the development of complications by keeping their blood sugar in a target range. They also need regular medical checkups to detect early signs of complications. If complications are treated early, the damage may be stopped, slowed, or possibly reversed.

People who have other health problems along with diabetes, such as high blood pressure or high cholesterol, need to treat those conditions. Also, not smoking can reduce the risk of complications. Having other health problems can increase the risk for complications from diabetes.

Preventing disease

Get a flu vaccine every year. When you have the flu, it can be harder to manage your blood sugar. It's a good idea to get a pneumococcal vaccine for pneumonia and a vaccine for hepatitis B.

You may need or want additional immunizations if certain situations raise your chance for exposure to disease.

Home Treatment

Type 1 diabetes requires daily attention to diet, exercise, and insulin. You may have times when this job feels overwhelming, but getting into a daily routine can help. And taking good care of yourself will also help you feel better, have a better quality of life, and prevent or delay complications from diabetes.

Spread carbohydrates throughout the day

Carbohydrate is the one nutrient in your diet that most affects blood sugar levels. A registered dietitian can help you learn about what foods contain carbohydrates and how to manage them in your diet.

Exercise regularly

Try to do moderate activity at least 2½ hours a week.footnote 1 One way to do this is to be active 30 minutes a day, at least 5 days a week.

Exercise safely. Drink plenty of water before, during, and after you are active. This is very important when it's hot out and when you do intense exercise. You can also try keeping track of your exercise on an activity log(What is a PDF document?).

If your doctor says it's okay, then try to do muscle-strengthening exercises at least 2 times a week. These exercises include push-ups and weight training. You can also use rubber tubing or stretch bands. You stretch or pull the tubing or band to build muscle strength. Be sure to work the major muscle groups: legs, hips, back, abdomen, chest, shoulders, and arms.

Protect your feet

Daily foot care can prevent serious problems. Foot problems caused by diabetes are the most common cause of amputations.

Limit alcohol

In addition to exercising, it is a good idea to limit the amount of alcohol you drink. The American Diabetes Association recommends that women with diabetes have no more than 1 drink a day and men with diabetes have no more than 2 drinks a day.footnote 2

Do not smoke

Having type 1 diabetes can cause a lot of problems in your body. Smoking can make many of these problems worse, especially heart and blood vessel disease.

Smoking raises your cholesterol and makes it harder for your body to heal.

No matter how long you've smoked, your health will improve after you quit.

Medications

Insulin

Insulin helps keep your blood sugar level tightly controlled and within a target range. It can be taken by an injection, or through an insulin pump. Rapid-acting insulin is also available as a powder that you inhale.

Usually people who have type 1 diabetes take a combination of types of insulin, such as a long-acting insulin once or twice a day and a rapid-acting insulin before each meal. The amount and type of insulin needed varies for each person.

The amount and type of insulin you need changes over time, depending on age, hormones (such as during rapid growth or pregnancy), and changes in exercise routine. You may need higher doses of insulin during times of illness or emotional stress.

Learn about insulin:

Know the dose of each type of insulin you take, when you take the doses, how long it takes for each type of insulin to start working (onset), when it will have its greatest effect (peak), and how long it will work (duration).

Daily aspirin

If you have talked about it with your doctor, take a low-dose aspirin every day. Aspirin can help certain people lower their risk of a heart attack or stroke. But taking aspirin isn't right for everyone, because it can cause serious bleeding. Do not start taking daily aspirin unless your doctor knows about it.

Medicines for other health problems

You may need one or more medicines to lower blood pressure.

You also may need to take medicine to lower your cholesterol.

Treating high blood pressure and high cholesterol may help prevent complications from diabetes.

You may need other medicines if you develop complications, such as kidney disease.

Surgery

Some complications from type 1 diabetes are treated with surgery. For example, surgery to remove the vitreous gel (vitrectomy) may improve eye disease.

Pancreatic islet cell surgery

Research continues on pancreatic islet cell surgery. It involves inserting a small group of donated pancreas cells (islet cells) through a vein in your liver. After surgery, these cells begin making insulin. If they can make enough, you may no longer need insulin injections.

Because the surgery is simpler than a pancreas transplant, there are usually fewer complications. But you must still take medicine to prevent rejection.

If you hear about something new to help diabetes, do some research to find out if it really works. You can also check with your doctor or a diabetes educator. Your health plan may also provide health information on its website.

Complementary therapies

Some complementary therapies may help relieve stress and muscle tension. They might help you feel better in general. But they shouldn't be used instead of treatment.

Other Works Consulted

Centers for Disease Control and Prevention (2017). National diabetes statistics report, 2017. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.pdf. Accessed December 1, 2017.

Pignone M, et al. (2010). Aspirin for primary prevention of cardiovascular events in people with diabetes: A position statement of the American Diabetes Association, a scientific statement of the American Heart Association, and an expert consensus document of the American College of Cardiology Foundation. Circulation, 121(24): 2694-2701.

Skyler JS, et al. (2009). Intensive glycemic control and the prevention of cardiovascular events: Implications of the ACCORD, ADVANCE, and VA Diabetes Trials: A position statement of the American Diabetes Association and a scientific statement of the American College of Cardiology Foundation and the American Heart Association. Diabetes Care, 32(1), 187-192.

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